function z=ptime(pmatrix,pos)
% This function computes the time domain representation of a periodic waveform
% from its spectral components at a given position. The output is a vector
% which contains the amplitude of waveform as a function of a scaled time
% (omega*tau) which runs from -pi to pi.
%
% by Ronald Kumon, 2 Dec 1995
% Declare global variables
global a n nhar
% Form waveform
Nsteps=50;
step=2*pi/Nsteps;
%z=zeros(1,Nsteps+1);
index = 1;
pvec =pmatrix(pos,:);
Avec =real(pvec);
Bvec =-imag(pvec);
for y=-pi:step:pi
compvec =Avec.*cos(n*y)+Bvec.*sin(n*y);
z(index)=sum(compvec);
index=index+1;
end